The present invention relates to a printer for printing characters one at a time to full page format by converting outline font data into bit map font data which is printed in every page.
A so-called electrophotographic printer has recently come into wide use for forming an electrostatic image on a photosensitive drum with use of a laser beam or the light of an LED in order to print printing data prepared by a personal computer, a word processor and the like on a print sheet.
The electrophotographic printer employs function formulae such as Bezier Mathematical Curves, Spline Mathematical Curves and the like which represent the outline of characters instead of the conventional dot matrix fonts (bit map fonts), and an outline font for storing therein connection points of the function formulas, and parameters and the like for controlling the connection points. Using this outline font, it is possible to change the sizes and formats of characters such as bold face and hollow outline with ease. However, the use of this outline font has the drawback of long processing times needed to generate bit map data based on this outline font. To solve the problem, a font cache memory is provided for avoiding the generation of the bit map font from the outline font when the same characters are reused, thereby to speed up the processing speed. That is, the first time that the bit map font is generated, the thus generated bit map font is stored in the font cache memory. When the same characters are printed again, they can be printed based on the bit map dated font in the font cache memory, thereby facilitating high speed printing.
Conversion of the outline fonts into the bit map fonts having the specific sizes is done using routines (and/or data) which are previously stored in the program for controlling the printer. Once the printer is turned on, the outline fonts are converted into the bit map fonts having the specific sizes which are instructed by the control program and stored in a font cache memory. When the printer (thereafter) receives a printing character code from a host unit such as a personal computer or word processor, the outline fonts will already have been converted into the corresponding bit map fonts.
Since the conventional printers are controlled by a variety of application programs, font types and character sizes are differentiated corresponding to the application programs to be used in the printers. The font types and the character sizes are also differentiated by users of the printers. Accordingly, even if the outline fonts are converted into the bit map fonts, the bit map fonts are not frequently used.
Since the types of the bit map fonts which are previously converted and stored in the printer are specified, the use of them results in a waste of time unless they match the type of the fonts to be used by the user.